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Journal of Experimental Botany Apr 2023Apomixis is considered a potentially revolutionary tool to generate high-quality food at a lower cost and shorter developmental time due to clonal seed production... (Review)
Review
Apomixis is considered a potentially revolutionary tool to generate high-quality food at a lower cost and shorter developmental time due to clonal seed production through apomeiosis and parthenogenesis. In the diplosporous type of apomixis, meiotic recombination and reduction are circumvented either by avoiding or failing meiosis or by a mitotic-like division. Here, we review the literature on diplospory, from early cytological studies dating back to the late 19th century to recent genetic findings. We discuss diplosporous developmental mechanisms, including their inheritance. Furthermore, we compare the strategies adopted to isolate the genes controlling diplospory with those to produce mutants forming unreduced gametes. Nowadays, the dramatically improved technologies of long-read sequencing and targeted CRISPR/Cas mutagenesis justify the expectation that natural diplospory genes will soon be identified. Their identification will answer questions such as how the apomictic phenotype can be superimposed upon the sexual pathway and how diplospory genes have evolved. This knowledge will contribute to the application of apomixis in agriculture.
Topics: Apomixis; Seeds; Reproduction, Asexual; Inheritance Patterns; Phenotype; Reproduction
PubMed: 36794770
DOI: 10.1093/jxb/erad054 -
Current Opinion in Biotechnology Feb 2023Apomixis is a process of asexual reproduction that enables plants to bypass meiosis and fertilization to generate clonal seeds that are identical to the maternal... (Review)
Review
Apomixis is a process of asexual reproduction that enables plants to bypass meiosis and fertilization to generate clonal seeds that are identical to the maternal genotype. Apomixis has tremendous potential for breeding plants with desired characteristics, given its ability to fix any elite genotype. However, little is known about the origin and dynamics of natural apomictic plant systems. The introgression of apomixis-related genes from natural apomicts has achieved limited success. Therefore, synthetic apomixis, engineered to include apomeiosis, autonomous embryo formation, and autonomous endosperm development, has been proposed as a promising platform to effectuate apomixis in any crop. In this study, we have summarized recent advances in the understanding of synthetic apomixis and discussed the limitations of current synthetic apomixis systems and ways to overcome them.
Topics: Apomixis; Plants; Seeds; Reproduction
PubMed: 36628906
DOI: 10.1016/j.copbio.2022.102877 -
Cell Host & Microbe Jun 2021The most widespread intracellular bacteria in the animal kingdom are maternally inherited endosymbionts of the genus Wolbachia. Their prevalence in arthropods and... (Review)
Review
The most widespread intracellular bacteria in the animal kingdom are maternally inherited endosymbionts of the genus Wolbachia. Their prevalence in arthropods and nematodes worldwide and stunning arsenal of parasitic and mutualistic adaptations make these bacteria a biological archetype for basic studies of symbiosis and applied outcomes for curbing human and agricultural diseases. Here, we conduct a summative, centennial analysis of living in the Wolbachia world. We synthesize literature on Wolbachia's host range, phylogenetic diversity, genomics, cell biology, and applications to filarial, arboviral, and agricultural diseases. We also review the mobilome of Wolbachia including phage WO and its essentiality to hallmark reproductive phenotypes in arthropods. Finally, the Wolbachia system is an exemplar for discovery-based science education using biodiversity, biotechnology, and bioinformatics lessons. As we approach a century of Wolbachia research, the interdisciplinary science of this symbiosis stands as a model for consolidating and teaching the integrative rules of endosymbiotic life.
Topics: Animals; Bacteriophages; Biological Evolution; Feminization; Host Microbial Interactions; Host Specificity; Humans; Male; Phenotype; Phylogeny; Preventive Medicine; Symbiosis; Wolbachia
PubMed: 33945798
DOI: 10.1016/j.chom.2021.03.006 -
The American Naturalist Aug 2022AbstractDetermining how and how often asexual lineages emerge within sexual species is central to our understanding of sex-asex transitions and the long-term maintenance...
AbstractDetermining how and how often asexual lineages emerge within sexual species is central to our understanding of sex-asex transitions and the long-term maintenance of sex. Asexuality can arise "by transmission" from an existing asexual lineage to a new one through different types of crosses. The occurrence of these crosses, cryptic sex, variations in ploidy, and recombination within asexuals greatly complicates the study of sex-asex transitions, as they preclude the use of standard phylogenetic methods and genetic distance metrics. In this study we show how to overcome these challenges by developing new approaches to investigate the origin of the various asexual lineages of the brine shrimp . We use a large sample of asexuals, including all known polyploids, and their sexual relatives. We combine flow cytometry with mitochondrial and nuclear DNA data. We develop new genetic distance measures and methods to compare various scenarios describing the origin of the different lineages. We find that all diploid and polyploid likely arose within the past 80,000 years through successive and nested hybridization events that involved backcrosses with different sexual species. All have the same common ancestor and therefore likely carry the same asexuality gene(s) and reproduce by automixis. These findings radically change our view of sex-asex transitions in this group and show the importance of considering scenarios of asexuality by transmission. The methods developed are applicable to many other asexual taxa.
Topics: Animals; Artemia; Parthenogenesis; Phylogeny; Polyploidy; Reproduction, Asexual
PubMed: 35905400
DOI: 10.1086/720268 -
Science (New York, N.Y.) Jun 2022Parthenogenetic grasshoppers confound predictions by showing no signs of decline.
Parthenogenetic grasshoppers confound predictions by showing no signs of decline.
Topics: Animals; Extinction, Biological; Grasshoppers; Parthenogenesis
PubMed: 35653466
DOI: 10.1126/science.abq3024 -
Methods in Molecular Biology (Clifton,... 2024The maternally transmitted reproductive manipulator Wolbachia can impact sex ratios of its arthropod host by different mechanisms, ultimately promoting the spread of...
The maternally transmitted reproductive manipulator Wolbachia can impact sex ratios of its arthropod host by different mechanisms, ultimately promoting the spread of infection across a population. One of these reproductive phenotypes, parthenogenesis induction (PI), is characterized by the asexual production of female offspring, which in many cases results in an entirely female population. Cases of Wolbachia-mediated PI are most common in the order Hymenoptera, specifically in parasitoid wasps. The complex sex determination pathways of hymenopterans, their diverse life histories, the multiple cytogenetic mechanisms of PI, and the lack of males make functional studies of parthenogenesis induction challenging. Here, we describe the mechanisms of PI, outline methods to recognize and cure PI-Wolbachia infection, and note possible complications when working with PI-Wolbachia strains and their parthenogenetic hosts.
Topics: Animals; Male; Female; Wolbachia; Parthenogenesis; Wasps; Reproduction
PubMed: 38006545
DOI: 10.1007/978-1-0716-3553-7_4 -
Journal of Equine Veterinary Science Apr 2021As standard in vitro fertilization is not a viable technique in horses yet, many different techniques have been used to create equine embryos for research purposes. One... (Review)
Review
As standard in vitro fertilization is not a viable technique in horses yet, many different techniques have been used to create equine embryos for research purposes. One such method is parthenogenesis in which an oocyte is induced to mature into an embryo-like state without the introduction of a spermatozoon, and thus they are not considered true embryos. Another method is somatic cell nuclear transfer (SCNT), in which a somatic cell nucleus from an extant horse is inserted into an enucleated oocyte, creating a genetic clone of the donor horse. Due to limited availability of equine oocytes in the United States, researchers have investigated the potential for combining equine somatic cell nuclei with oocytes from other species to make embryos for research purposes, which has not been successful to date. There has also been a rising interest in producing transgenic animals using sperm exposed to exogenous DNA. The successful creation of transgenic equine blastocysts shows the promise of sperm mediated gene transfer (SMGT), but this method is not ideal for other applications, like gene therapy, because it cannot be used to induce targeted mutations. That is why technologies like CRISPR/Cas9 are vital. In this review, we argue that parthenogenesis, SCNT, and interspecies SCNT can be considered genetic manipulation strategies as they create embryos that are genetically identical to their parent cell. Here, we describe how these methods are performed and their applications and we also describe the few methods that have been used to directly modify equine embryos: SMGT and CRISPR/Cas9.
Topics: Animals; Blastocyst; Embryo, Mammalian; Horses; Male; Nuclear Transfer Techniques; Oocytes; Parthenogenesis
PubMed: 33781418
DOI: 10.1016/j.jevs.2021.103394 -
Annals of Botany Jun 2024The predominance of sex in eukaryotes, despite the high costs of meiosis and mating, remains an evolutionary enigma. Many theories have been proposed, none of them being... (Review)
Review
BACKGROUND
The predominance of sex in eukaryotes, despite the high costs of meiosis and mating, remains an evolutionary enigma. Many theories have been proposed, none of them being conclusive on its own, and they are, in part, not well applicable to land plants. Sexual reproduction is obligate in embryophytes for the great majority of species.
SCOPE
This review compares the main forms of sexual and asexual reproduction in ferns and angiosperms, based on the generation cycling of sporophyte and gametophyte (leaving vegetative propagation aside). The benefits of sexual reproduction for maintenance of genomic integrity in comparison to asexuality are discussed in the light of developmental, evolutionary, genetic and phylogenetic studies.
CONCLUSIONS
Asexual reproduction represents modifications of the sexual pathway, with various forms of facultative sexuality. For sexual land plants, meiosis provides direct DNA repair mechanisms for oxidative damage in reproductive tissues. The ploidy alternations of meiosis-syngamy cycles and prolonged multicellular stages in the haploid phase in the gametophytes provide a high efficiency of purifying selection against recessive deleterious mutations. Asexual lineages might buffer effects of such mutations via polyploidy and can purge the mutational load via facultative sexuality. The role of organelle-nuclear genome compatibility for maintenance of genome integrity is not well understood. In plants in general, the costs of mating are low because of predominant hermaphroditism. Phylogenetic patterns in the archaeplastid clade suggest that high frequencies of sexuality in land plants are concomitant with a stepwise increase of intrinsic and extrinsic stress factors. Furthermore, expansion of genome size in land plants would increase the potential mutational load. Sexual reproduction appears to be essential for keeping long-term genomic integrity, and only rare combinations of extrinsic and intrinsic factors allow for shifts to asexuality.
Topics: Apomixis; Magnoliopsida; Reproduction, Asexual; Biological Evolution; Ferns; Reproduction; Phylogeny; Meiosis; Plants
PubMed: 38497809
DOI: 10.1093/aob/mcae044 -
Genome Biology and Evolution Jul 2023Cyclical parthenogenesis, where females can engage in sexual or asexual reproduction depending on environmental conditions, represents a novel reproductive phenotype...
Cyclical parthenogenesis, where females can engage in sexual or asexual reproduction depending on environmental conditions, represents a novel reproductive phenotype that emerged during eukaryotic evolution. The fact that environmental conditions can trigger cyclical parthenogens to engage in distinct reproductive modes strongly suggests that gene expression plays a key role in the origin of cyclical parthenogenesis. However, the genetic basis underlying cyclical parthenogenesis remains understudied. In this study, we characterize the female transcriptomic signature of sexual versus asexual reproduction in the cyclically parthenogenetic microcrustacean Daphnia pulex and Daphnia pulicaria. Our analyses of differentially expressed genes (DEGs), pathway enrichment, and gene ontology (GO) term enrichment clearly show that compared with sexual reproduction, the asexual reproductive stage is characterized by both the underregulation of meiosis and cell cycle genes and the upregulation of metabolic genes. The consensus set of DEGs that this study identifies within the meiotic, cell cycle, and metabolic pathways serves as candidate genes for future studies investigating how the two reproductive cycles in cyclical parthenogenesis are mediated at a molecular level. Furthermore, our analyses identify some cases of divergent expression among gene family members (e.g., doublesex and NOTCH2) associated with asexual or sexual reproductive stage, suggesting potential functional divergence among gene family members.
Topics: Parthenogenesis; Transcriptome; Reproduction, Asexual; Male; Female; Animals; Daphnia; Gene Expression Profiling
PubMed: 37392457
DOI: 10.1093/gbe/evad122 -
Genes Aug 2020In the past decades, the grasses of the genus have emerged as a versatile model allowing evolutionary, genetic, molecular, and developmental studies on apomixis as well... (Review)
Review
In the past decades, the grasses of the genus have emerged as a versatile model allowing evolutionary, genetic, molecular, and developmental studies on apomixis as well as successful breeding applications. The rise of such an archetypal system progressed through integrative phases, which were essential to draw conclusions based on solid standards. Here, we review the steps adopted in to establish the current body of knowledge on apomixis and provide model breeding programs for other agronomically important apomictic crops. In particular, we discuss the need for previous detailed cytoembryological and cytogenetic germplasm characterization; the establishment of sexual and apomictic materials of identical ploidy level; the development of segregating populations useful for inheritance analysis, positional mapping, and epigenetic control studies; the development of omics data resources; the identification of key molecular pathways via comparative gene expression studies; the accurate molecular characterization of genomic loci governing apomixis; the in-depth functional analysis of selected candidate genes in apomictic and model species; the successful building of a sexual/apomictic combined breeding scheme.
Topics: Apomixis; Gene Expression Regulation, Developmental; Gene Expression Regulation, Plant; Models, Biological; Paspalum; Plant Breeding; Plant Proteins; Seeds
PubMed: 32839398
DOI: 10.3390/genes11090974